Colour vision deficiency (colour blindness)Overview

People with colour vision deficiency find it difficult to identify and distinguish between certain colours.

It's sometimes called being "colour blind", although total colour blindness (an inability to see any colour) is very rare.

Colour vision deficiency is usually passed on to a child by their parents (inherited) and is present from birth, although sometimes it can develop later in life.

Most people are able to adapt to colour vision deficiency and it's rarely a sign of anything serious.

Types and symptoms of colour vision deficiency

Most people with colour vision deficiency have difficulty distinguishing between shades of red, yellow and green.

This is known as "red-green" colour vision deficiency. It's a common problem that affects around 1 in 12 men and 1 in 200 women.

Someone with this type of colour vision deficiency may:

find it hard to tell the difference between reds, oranges, yellows, browns and greens

see these colours as much duller than they would appear to someone with normal vision

have trouble distinguishing between shades of purple

confuse reds with black

In rare cases, some people have trouble with blues, greens and yellows instead. This is known as "blue-yellow" colour vision deficiency.

Tests for colour vision deficiency

Ask for a colour vision test at an opticians if you think you or your child may have a colour vision deficiency, particularly if it started suddenly or is getting worse.

Colour vision tests do not usually form part of the routine NHS eye test, but you can specifically ask for them.

Two of the main tests used to diagnose colour vision deficiency are:

the Ishihara test, where you're asked to identify numbers contained within images made up of different coloured dots

colour arrangement, where you're asked to arrange coloured objects in order of their different shades

There are a number of online tests using similar techniques that may help detect a possible problem, but it's best to have a proper test at an opticians if you have any concerns about your colour vision.

Issues for people with a colour vision deficiency

Colour vision deficiency is not usually anything to be concerned about.

Most people get used to it over time, it will not normally get any worse, and it's rarely a sign of anything serious.

But it can sometimes cause issues such as:

difficulty at school if colours are used to help with learning

problems with food, such as identifying whether meat is fully cooked or whether fruit is ripe

Overall, many people with a colour vision deficiency have few, if any, difficulties. They can do most normal activities, including driving.

Treating and living with a colour vision deficiency

There's currently no cure for inherited colour vision deficiency, although most people are able to adapt to it over time.

It may help to:

tell your child's school if they have problems with their colour vision so learning materials can be adapted accordingly

ask your friends or family for help – for example, they can help you choose matching clothes and check whether food is safe to eat

install good-quality lighting in your home to help you distinguish colours

make use of technology – computers and other electronic devices often have settings you can change to make them easier to use, and there are a number of mobile phone apps available that can help identify colours for you

try special tinted lenses – these are worn in 1 or both eyes to help you distinguish between certain colours, although they only seem to work for some people